For a variety of reasons, most of which relate to environmental and alternative energy pursuits, certain primary fuel engines, such as diesel engines, can be made to accommodate alternate fuels, such as straight vegetable oil (SVO), “biodiesel,” and other fuel oils (hereinafter “alternate fuels”). However, practical applications have demonstrated that some alternate fuels cannot be used in their pure or neat form under all engine and environmental conditions and must be blended with the primary fuel.
Recently, one method for the creation of motor fuels with alternate fuel content has been accomplished by blending primary and alternate fuels at or before the end user distribution point at low ratio to ameliorate alternate fuel negative attributes such as higher viscosity and the tendency to congeal at low temperatures, a common example being twenty percent alternate fuel to eighty percent primary fuel by volume. While this has benefit in allowing most engines designed to run on diesel to utilize a degree of alternate fuel, this methodology constrains the end user to a fixed ratio designed for worst-case utilization conditions, and in doing so effectively forfeits optimal utilization of the alternate fuel as actual end use conditions would otherwise permit.
To fulfill the requirements of introducing renewable fuel into the national fuel supply, the U.S. Environmental Protection Agency (EPA) Renewable Fuel Standard of 2007 (RFS1) was enacted under the Energy Policy Act of 2005, and amended in 2008 (RFS2), increasing the amount of renewable fuel mandated by the requirements; said renewable fuel to be blended with fossil fuel.
Traditionally, EPA Renewable Fuel Standard (hereinafter, “RFS”) compliant blending is performed in large batches during the process of filling a mobile tanker delivery vehicle at a fuel distribution facility. Pursuant to the RFS, a fossil fuel feedstock and a renewable fuel feedstock are blended to produce a motor fuel for distribution and sale, those feedstocks most commonly being gasoline and anhydrous ethanol, or diesel and biodiesel, each being added using a metered delivery mechanism to a mobile tanker delivery vehicle to simultaneously obtain both a desired blend ratio and a desired total volume. This process is commonly referred to as “splash blending” and/or “rack blending”; splash being vernacular for the two fuel types being summarily dispensed into tanker vessel, being mixed by splash turbulence and/or innate miscibility; “rack” being vernacular for the tanker delivery vehicle filling apparatus.
Also pursuant to RFS, by the process of having blended the two feedstocks, a fungible value that is associated with the renewable fuel's Renewable Identification Number (hereinafter, “RIN”) is “detached” in one bulk step, with the detached RINs then becoming available for sale, and once posted for sale, “retired”. Obligated parties, those being fossil fuel producers or fossil fuel importers, are required to purchase retired RINs at market value; with supply, demand, and other market forces determining price.
It is important to understand that the assigned RIN, (at time of” writing) a 36-digit number comprising multiple fields, remains with the renewable fuel until combusted or otherwise consumed. More specifically, the first digit of the RIN, whose field is designated using the letter “K”, has the value of “1” (one) when the fungible portion is attached, and becomes “2” (two) once the fungible portion is detached upon blending. Consequently, the RIN, with K=2, continues forward with the renewable fuel until combustion. Nevertheless, in industry vernacular, the fungible detached and/or retired component is also commonly referred to as a RIN.
While splash blending of fossil and renewable fuels prior to delivery is accepted and commonplace, limitations occur.
The RIN, once detached during splash blending, is no longer forward traceable to time and place of consumption; therefore there is no record of traceability that it was consumed in proper manner, that being its utilization as an offset displacing fossil fuel consumption.
Correspondingly, the RIN not being traceable to time and place of consumption, the associated CO2 offset provided by the renewable fuel is furthermore not traceable to time and place of offset.
For gasoline and anhydrous ethanol, the maximum ratio of the anhydrous ethanol feedstock is limited by the tolerance of the general population of vehicles to anhydrous ethanol, it being corrosive to aluminum, other metals, and some polymers. Consequently, its blend ratio for general consumption (at the time of this writing) is limited to 10%.
For diesel and biodiesel, the maximum ratio of the biodiesel is limited by the tendency of biodiesel to cloud at temperatures common during winter, and when heated by virtue of constant circulation with a diesel engine's fuel system, its tendency to form corrosive acids. Consequently, its blend ratio for general consumption is generally limited to 5% during winter months, and 20% during summer months.